Super-hydrophobic metals now a reality

Scientists at the University of Rochester (USA) have used lasers to make metals ultra water repellent, opening a world of possibilities for these amazing materials.

About the author

Joanne McIntyre is the Editor in Chief of Stainless Steel World magazine, and Conference Coordinator for the Duplex Seminar & Summit.

Every now and again an innovation comes along that makes you sit up and take notice, and Professor Chunlei Guo has provided just such an inspiring development. His team at the University of Rochester’s Hajim School of Engineering and Applied Sciences have developed a powerful and precise laser-patterning technique that creates an intricate pattern of micro- and nanoscale structures. “The structures created by our laser on the metals are intrinsically part of the material surface. That means they won’t rub off” explains the Professor.
The work actually builds on earlier research by the same team, which used a similar laser-patterning technique to turn metals black and make them ultra-light absorbent. Professor Guo states that using this technique, they can create multifunctional surfaces that are not only super-hydrophobic but also highly-absorbent optically.

Hydro-what?

So how water repellent are these materials when they are actually exposed to water? The answer is ‘extremely’! The best way to understand the level of hydro-phobia achieved is to watch the following short video which shows how water droplets literally bounce themselves off the metal.

You may be asking why this development is significant, and the answer is surprisingly simple. The laser treated material is so hydro-phobic that it is essentially self-cleaning; water droplets not only bounce off so the metal stays dry, they also remove any dust or other dirt so it’s self-cleaning. Possible applications include water collection and sanitary uses; imagine toilets that don’t need to be cleaned, saving water and improving hygiene enormously in poor regions. For this reason the Bill & Melinda Gates Foundation is supporting the research.

“In these regions, collecting rain water is vital and using super-hydrophobic materials could increase the efficiency without the need to use large funnels with high-pitched angles to prevent water from sticking to the surface,” says Prof. Guo. “A second application could be creating latrines that are cleaner and healthier to use.”

The US Air Force Office of Scientific Research is also supporting the research and sees potential for hydro-phobic metals for anti-icing and anti-corrosion applications and for reducing water friction for ships.